Ag nanoparticles were successfully prepared using a liquid reduction method with a suitable mixture reductant of polyethylene glycol (PEG) and ethylene glycol (EG). OP-10 as a dispersing agent, was used to prepare the conductive Ag ink. Ag nanoparticles with an average particle size of 40 nm were prepared while the ratio of PEG to EG was 1:2. Meanwhile, the Ag particles had a narrow size distribution and great dispersion performance. The effects of paper substrates, sintering temperature, and sintering time on the conductivity of the printed Ag ink pattern were also studied. It was found that Lucky porous high glossy photo paper was a good candidate as the printing substrate. The resistivity of the printed pattern could reach 5.1 × 10⁻³ Ω·cm after heated at 100 °C for 2 h. Hence, the printed pattern showed good conductivity which led to the LED light being on. Furthermore, the Ag nanoparticle ink could be printed to form any pattern as required that still showed good electrical conductivity after being sintered under low-temperature. This could provide new possibilities for the preparation of flexible electrodes.

Titanium (Ti) and Ti-based alloy are widely used in the biomedical field owing to their excellent mechanical compatibility and biocompatibility. However, the bioinert bioactivity and biotribological properties of titanium limit its clinical application in implants. In order to improve the biocompatibility of titanium, we modified its surface with TiO_x/TiN_x duplex composite films using a new method via micro-arc oxidation (MAO) and nitrogen ion implantation (NII) treatment. The structural characterization results revealed that the modified film was constructed by nanoarrays composed of TiO_x/TiN_x composite nanostitches with a size of 20~40 nm. Meanwhile, comparing this with pure Ti, the friction property, wear resistance, and bioactivity were significantly improved based on biotribological results and in vitro bioactivity tests.

As for metal matrix composites (MMCs), the selection and application of reinforcements play a vital role in their comprehensive properties. In this work, the CrCoNi medium entropy alloy (MEA) was selected as reinforcement for Al matrix composites, and the effects of the content of the CrCoNi MEA on the mechanical properties and friction resistance were systematically investigated. It was found that the CrCoNi MEA can effectively improve the mechanical properties of the Al matrix composites, especially the 5 wt.% CrCoNi/Al composite can achieve a high strength without the sacrifice of ductility, due to the strengthened interfacial bonding between the Al matrix and the CrCoNi reinforcements caused by the element interdiffusion and the high mechanical performance of the CrCoNi MEA itself. In addition, the wear resistance of the composites can be enhanced by the inclusion of the CrCoNi MEA reinforcement, because the CrCoNi MEA can substantially improve the hardness of the composites and promote the formation of the oxidative protection film during the friction process. This work paves a new route for preparing Al matrix composites with high mechanical properties and friction resistance.